Inserting & Updating Related Models: The Create Method

$post = App\Post::find(1);

$comment = $post->comments()->create([
    'message' => 'A new comment.',
]);

$post = App\Post::find(1);

$post->comments()->createMany([
    [
        'message' => 'A new comment.',
    ],
    [
        'message' => 'Another new comment.',
    ],
]);